The present invention relates to an operational amplifier arrangement, and more particularly operational amplifier arrangements which can be used as line drivers in telecommunication line circuits.
Line driver circuits are already known in the art and comprise the classical class-G-based operational amplifiers such as these for instance described in published European Patent Applications 1 024 592 and 1 024 591. Other line driver circuits are based on switching line drivers such as the one described in the published European Patent Application 1 229 641. Yet other types of line drivers are based on class C-AB architectures, such as these disclosed in published European Patent application 1 220 442 and 1 220 443. Key issues for line drivers in applications such as ADSL, which is the abbreviation of asymmetric digital subscriber line, are the power efficiency, the linearity and the complexity. Although all types of above-mentioned line drivers were conceived such as to optimize these issues, yet there remains a need for improvement of the power efficiency, and linearity, while at the same time keeping the complexity of the operational arrangement as low as possible. This is especially important for very high speed digital subscriber line applications, hereafter abbreviated with VDSL.